> What did you modify within M5?  One of those modifications may be 
> causing the CPU to go down the wrong path and try to access a bad 
> address.

I've added some more stats to the caches so it *shouldn't* be causing
any functional differences...

> Unfortunately the CPU doesn't have many debugging statements, 
> so it may be a bit difficult to track down if you think the error is in 
> the CPU itself.  You might want to start by turning on some trace flags 
> to see if the instructions executed at least look correct.  You can do 
> this by using --Trace.flags="InstExec".  You can also use "Bus" and 
> "Cache" as parameters to see if the memory stream looks correct as 
> well.  If you're able to find something wrong, you can narrow down the 
> cycles you need to look at and possibly step through the CPU with GDB or 
> add some debugging statements yourself.  There's also an option for 
> --Trace.start=<cycle>, which helps limit the amount of output you get.

Unfortunately the bogus memory operation only seems to happen several
hundred million cycles in so it's a long wait!
 
> If you're running in non-full system mode, then you might be able to use 
> the tracediff utility to compare the output of two configurations.  It's 
> in the util directory; just open it up and it has instructions inside of 
> it (it's a short script).  Generally I run this with the common option 
> of "--Trace.flags="InstExec" 
> -P"root.exetrace=ExecutionTrace(print_cycle=False)" " in order to 
> compare output of two configurations.  Beware that if you have 
> interrupts or results dependent on your configuration (such as the Rpcc 
> instruction), this may work only if your error is early on.

Thanks, I am running in SE mode. I'll take a look at dumping and diffing
some traces. I was afraid it might come to this. Current theory is that
the case that works hits in the LSQ whereas the one which doesn't work
misses but it's just a stab in the dark.

Thanks again,

James

-- 
[EMAIL PROTECTED]
http://www.cl.cam.ac.uk/~jrs53/


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